docs: def kml_region(map_source, z, x, y):
      """KML region fetched by a Google Earth network link. """
      map = app.config["mapsources"][map_source]
      kml_doc = KMLRegion(app.config["url_formatter"], map, app.config["LOG_TILES_PER_ROW"],
                          z, x, y)
      return kml_response(kml_doc)